Novel X‐shaped conjugated oligothiophenes, which form a family of well‐defined C4‐substituted compounds with a core thiophene ring that bears four short‐chain branches containing α–α and α–β linkages, have been designed and synthesized by a facile synthetic route. Their optoelectronic properties can be electronically fine‐tuned by manipulating the segments of the branches. In solution, the four compounds show strong photoluminescence with emission maxima located at 459, 491, 494, and 547 nm. The optical properties of their films suggest an interesting conjugated effect in these X‐shaped oligomers. Cyclic‐voltammetry measurements of these compounds have been performed, and corresponding stable polymers from two of the monomers have been prepared by electrochemical polymerization. UV–vis absorption and emission properties of the resultant electroactive polymers are studied, indicating that the optical properties of the 3D polymers could be controlled by repeated potential scans.

COMMUNICATION 3038www.advmat.de

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Novel butterfly pyrene derivatives functionalized with trifluoromethylphenyl and thienyl aromatic groups in the 1-, 3-, 6- and 8-positions of pyrene cores and have been synthesized by Suzuki coupling reactions, and their crystal structures, optical and electrochemical properties investigated; additionally, the field effect transistor using as the active material exhibited a p-type performance.

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In this paper, the saturated practical stabilization problem is addressed for a class of nonholonomic mobile robots based on visual servoing feedback with uncertain camera parameters. The new switching control design method to be proposed is directly based on the original system, which can avoid the problem of singularity arising from state or input transformation. A saturated discontinuous controller is presented by applying the multi-step switching control strategy and the theory of finite-time stability. The closed-loop system can be stabilized to a prescribed arbitrarily small neighborhood of the zero equilibrium point in a finite time. Finally, the simulation results show the effectiveness of the proposed controller design approach.

A novel type of anti and syn isomers of a pentacyclic compound consisting of two thiophene rings and one pyrrole ring were efficiently synthesized from benzo[b]thiophene, and the anti isomer exhibits better charge transport and OFET properties compared with the syn isomer and its N-hexyl substitution.